Coal mining machine



N. D. LEVIN QOAL MINING MACHINE Original Filed Sept. 4, 1926 4 Sheets-Sheet 1 .Q 0 N & 5 Q. N w E.

1 i a. 5n u- J V M 1 3 H h h on v 1 IT a w .5. sh h V 0 5M Oct. 23,1934. N. 0. LEVIN 1,978,367

COAL MINING MACHINE Original Filed Sept.-4, 1926 4 Shets-Sheet 2 ulmummm Oct. 23, 1934. N. D. LEVIN COAL MINING MACHINE 4 sheds-sheet 3 Original Filed Sept. 4, 1926 lad 7/11 7671/17 r R3 1 I kg u /III/III{IIIII/IlI/IIIIl/IIIIIIII/IIIII/IIIII/VIII]IIIII/Ill !II/Il/IIIIIIIIIIIII/IIl/Im/Iall]lIIIIIII/IIIIIIIIIIIII' all.

Oct. 23, 1934. N, D) LEVIN 1,978,367

COAL MINING momma Origipal File d Sept. 4. 1926 4 Sheets-Sheet 4 I I 5N2 2-- air, Illllrll;

Patented Oct. 23,1934

oFFIc 1,978,367 COAL MINING MACHINE Nils D. Levin, Columbus, Ohio, asslgnor to The Jeffrey Manufacturing Company, Columbus, Ohio, a corporation of Ohio Application September 4, 1926, Serial No.

Renewed January 5, 1932 (1 Claims. (01. 262-9) The present invention relates to certain new and useful improvements in coal miningmachines, 'of the class in which each machine is provided with traction wheels, and is adapted to perform its mining operations while supported upon said wheels.

It is the especial object of this invention to pro-: vide, in a machine of the class described, improved cutting mechanism adapted to be moved in a vertical plane to form a kerf extending from the floor to the roof of the mine.

A further object is to provide a machine adapted for cuttingas aforesaid, and having means to receive the cuttings produced by the kerf cutter and remove them transversely of the machine.

A further object is to provide a machine for cutting as aforesaid, and for simultaneously forming suitably placed holes in the coal body to receive the explosivecharges whereby the coal is dislodged from its native bed.

A further object is to provide improved devices for positioning and supporting the drilling mechanism by which said blasting holes are 25 formed.

The means whereby I attain these objects are fully set forth in the following specification, and illustrated in the accompanying drawings of which ment of my invention.

Fig. 2 is a side elevation of the machine illustrated in Fig. 1.

Fig. 3 is a sectional view taken along the line III-III of Fig. 1.

Fig. 4 is a fragmentarysectional view taken along theline IV-IV of Fig. l.

Fig. 5 is a fragmentary sectional view taken along the line V-V of Fig. 1.

Fig. 6 is a sectional view taken along the line VI-VI of Fig. 1.

Fig. '7 is a fragmentary sectional view taken along the line VIIVII of Fig. 1.

Fig. 8 is a diagrammatic plan view of the cutter supporting and operating mechanism.

Fig. 9 is a fragmentary sectional view along the line IX--IX of Fig. 8.

Fig. '10 is a fragmentary sectional view taken along the line X--X of Fig. 1. Fig. 11 is a fragmentary view of the clutch shifting mechanism. I

.Fig. 12 is a fragmentary detail of the drill feed mechanism. I

Like numerals refer to similar parts in the several figures.

taken Fig. 1 is a plan view of the preferred embodicurrent from any suitable source of electric sup- .5

ply through a flexible conductor cable 5. The cable 5 is adapted to be wound upon a cable reel 6 which is arranged to pay out the cable as the machine moves away from its point of connection with the supply conductors, and to automatically wind up said cable as the machine moves towards said connection. Mounted upon the front part of the truck body 1 is a gear housing 7 within which is mounted the power transmission mechanism whereby the motor 4 is connected with the traction wheels 2, as by a chain 2' to propel the machine along the rails 3. This transmission mechanism preferably includes devices whereby the speed of rotation of the track wheels may be optionally controlled to propel the machine at a relatively high speed suitable for traveling from one working place to another, or at relatively low speed suitable for feeding the cutting mechanism into the coal. Since all of the above devices are fully described in United 86 States Patent #1,565,376, and since here they enter only generally in the combination to be claimed, it is not thought necessary to describe them specifically here.-

Mounted in a suitable bearing 8 of the sup- 90 porting frame '1 is a cylindrical sleeve 9 the axis of which extends transversely of the truck body 1. Securedtothesleeve9byakey loisahub 11 which is formed integral with the cutter frame 12. The cutter frame 12 projects longitudinally from-the forward end of the machine in a vertical plane substantially central of the truck frame 1. Upon the lateral edges of the cutter frame 12 are formed guideways wherein travels the cutter chainv 13 in the usual and well known manner.

Mounted concentric with the sleeve 9 is a power shaft'l! to which is fixed a sprocket wheel 15 which engages the cutter chain 13 to drive it. Mounted for free rotation'upon the shaft 14.

is a pair of oppositely disposed bevel gears 16 and 1'! both of which are engaged by the bevel pinion 18 fixed to the forward end of the longitudinally extending power shaft 19. To the rearward end of the shaft 19 is fixed a spur gear 20 1-10 motor 4. Longitudinally slidable upon the shaft 14, between the bevel gears 16 and 1'7, and connected to said shaft by a suitable key, is a double face jaw clutch 22 the jaws of which are adapted to engage corresponding jaws formed upon the bevel gears 16 and 1'? to alternately connect either of said gears with said shaft. The shifting lever 23 is arranged to move said clutch into engagement with either or neither of said bevel gears, and to hold it in the preferred position.

Keyed to the free end of the sleeve 9 is a downwardly projecting crank arm 24 having crank pin 25 which is engaged by the connecting rods 26. At their rearward ends the connecting rods 26 engage the stud pins 27 which project laterally from the nut 28 in screw threaded engagement with the longitudinaliy extendingscrew shaft 29. The nut 28 is slidable in guideways 30 of the supporting frame, by which it is held against rotation with the screw shaft 29. The screw shaft 29 is held against longitudinal movement by the journal bearings 31 and 32 of the supporting frame, and is adapted to be rotated by power derived from the power shaft 19 through a longitudinally extending driving shaft 33. Fixed to the screw shaft 29 near its rearward end are two spur gears 34 and 35 which are of different diameters, and these are adapted to be engaged by the spur gears 36 and 37 respectively. The gears 36 and 37 are formed integral with the sleeve 38 which issplined to the shaft 33. Formed on the sleeve 38 is a circumferential groove 39 which is engaged by a shifting fork 40 attached to the rock shaft 41. For convenience of operation all of the control devices are grouped at the left hand side of the truck frame, and the rock shaft 41 is connected with the conveniently positioned operating lever 42 through a transversely extending shaft 43 the rocker arms 44 and 45 and the connecting link 46. By manipulation of the operating lever 42, the sleeve 38 may be moved longitudinally of the shaft 33 to bring the gear 3'! into engagement with the gear 35 causing the screw shaft 29 to revolve at relatively high speed. or to move the gear 36 into engagement with the gear 34 to cause rotation of the screw shaft 29 at relatively slow speed. The proportions of these parts are such that the sleeve 38 may beheld in a central neutral positioni'permitting the shaft 29 to remain idle. The power shaft 19 is preferably formed in two parts to each of which is fixed a flange coupling 19a, and these flange couplings are rotatively connected by a shear pin 19b, formed of hard wood or other suitable material, by the shearing of which the power devices of the machine are protected against undue strain caused by the jamming of the cutter mechamsm.

Freely rotatable upon .the shaft 33 is a spiral gear 47 which is driven by'a cooperating spiral gear 48 fixed to the power shaft 14. A radially extending flange formed integral with the spiral gear 4'7 is in contact with a similar flange 49 formed upon the hub 50 which is keyed to the driving shaft 33. A pin 51, formed of hard wood or other suitable material, extends through aligned apertures in the flanges 4'1 and 49 to operatively connect the spiral gear 47 with the shaft 33. When, for any reason, the resistance to rotation of the shaft 33 exceeds a predetermined limit of safety, the pin 51 shears between the flanges 4'7 and 49 thus protecting the 8P- paratus from excessive strain.

1,978,867 which engages the armature pinion 21 of the In the operation of my improved coal cutting machine, the truck 1 is propelled along the mine track at a relatively high speed, into proximity with the coal face wherein the kerf is to be cut.

The shifting lever 23 is then manipulated to cause engagement of the clutch 22 with the appropriate bevel gear to cause rotation of the power shaft 14 in the anti-clockwise direction as viewed in Fig. 4 of the drawings. The gear 3'? is then moved into engagement with the gear 35 causing the screw shaft 29 to revolve at a relatively high speed in such direction that the nut 28 will be moved forwardly, causing the crank arm 24 to rotate about the axis of the shaft 14, and quickly elevate the free end of the cutter arm 12. When the cutter arm has been elevated to the line of the mine roof, the gear 37 will-be moved out of engagement with the gear 35 stopping rotation of the screw shaft 29, and thereby locking the cutter arm in its elevated position. The clutch lever 23 may then be shifted to reverse the direction of rotation of the shaft 14, driving the sprocket wheel 15 in a clockwise direction, as viewed in Fig. 4, causing the cutter chain 13 to travel in" the coal cutting direction. The truck 9 propellingmechanism is then actuated to move the machine bodily forward upon the track rails at its relatively low speed which is suitable for feeding the cutting mechanism into the coal. When the cutter arm has been thrust into the coal to the desired depth, the machine is halted, the gear 36 moved into engagement with the gear 34, rotating the screw shaft 29 at a relatively low speed and in a direction to produce downward movement of the free end of the cutter bar. After completion of the downward cut, the truck is moved bodily rearwardly at its lower speed to withdraw the cutter bar from the coal to finish the kerf. The cutter bar is then elevated sufliciently to clear the mine tracks and the machine proceeds at its traveling speed to the next working place.

During the vertical cutting operation, the truck body 1 occupies a position relatively close to the coal face, and coal cuttings dragged from the kerf by the cutter chain will, if not removed, accumulate in front of the machine in sufficient quan- .tities to interfere with proper operation of the travel around the sprocket wheels 53 and 54.' Thesprocket wheel 54 is supported by a shaft 55 mounted in suitable bearings of the supporting frame, and the sprocket wheel 53 is fixed to a shaft 56 which extends longitudinally of the machine and is connected to the power shaft 14 by a pair of bevel gears 57 and 58. Attached to the chain 52 at convenient intervals are the scraper flights 59 adapted to propel material along the trough 60 which is formed in the lower part of the conveyor casing 61. At the forward side of the casing 61, immediately in the rear of the sprocket wheel 15, there is formed a window 62 through which the coal cuttings may be propelled by the centrifugal force of the cutter chain traveling around the sprocket wheel 15. The coal cuttings thus received in the trough 60 are propelled therealong by the scrapers 59 and discharged through the open end of the casing at the side of the machine. The idler roller 63 is provided to hold the conveyor chain 52 clear of the power shaft 19. Y

Positioned midway the length of the truck frame 1, and extending transversely thereof, is a channel bar 84 which is supported at each end by a suitable plate 65 secured to the side members of the frame. Mounted upon the channel bar 64 for pivotal movement about vertical axes are the brackets 66 which support the drilling mecha-. nism. There are preferably, though not nee-- which extends the bar 6'7 upon the end of which:

is supported the drilling mechanism proper. In order to secure maximum rigidity of support with minimum weight I have here proposed a supporting bar 67 of rectangular cross section, built up of suitable plates electrically welded together, but it is to be understood that a bar of any other form or construction may be. used if desired. At each end of the passage in the bracket 66 there is mounted an anti-friction roller 68 adapted to support the weight of the bar 6'? and to facilitate its longitudinal movement. A. clamping screw 69 is also provided upon the brackets 66 whereby said bar may be secured in the preferred position of longitudinal adjustment, and a rod '10 connected at one end with the bar 67' and at the other adapted to engage the appropriate aperture '11 of the. flange 72 of the supporting frame serves to maintain the said bar in the desired angular relation. To the outer end of the bar 6'? is attached a socket 73 in which is pivotally mounted for rotation about its vertical axis, a yoke '74 having journal bearings '15 adapted toengage trunnions formed upon the drilling mechanism and upon which said mechanism may be tilted in vertical planes.

The drilling mechanism proper comprises a motor '16 which is preferably an electric motor actuated by electric current derived through suitable flexible conductors 7'7 and controlled by a controlling switch '18 conveniently mounted upon the bracket 66. The controlling switch '18 here illustrated is of a well known construction especially adapted to use in coal mines, and,as it forms no part of the present invention, further description and illustration is not thought to be required at this time. Extending through the electric motor 76 is a feed shaft 79 which is so connected with the moving parts of the motor as to be rotated thereby while remaining free to move longitudinally therein. At the outer end of the feed shaft 79 I have provided a socket 80 adapted to receive a drill bit 81 of the well known auger type adapted to bore relativelydeep holes in the coal body when rotated. Formed upon the feed shaft '79 is a screw thread adapted to engage the feed nut 82 by which the shaft 79 may be forced longitudinally towards the coal face when said shaft revolves. The feed nut 82 is formed in two parts hinged together in such manner that they may be moved completely out of engagement with the threads upon the feed shaft to permit longitudinal adjustment of said shaft, or they may be drawn together by the clamping screw 83 to hold them in feeding engagement with said thread. By further tightening of the screw 83 the parts 82 may be tightly clamped upon the screw shaft to revolve with it. The nut 82 is attached to a cylindrical body 84 rotatively mounted upon an extension 85 of the motor frame concentric with the feed shaft 79. A brake band 86 adapted to engage the periphery of the-cylindrical body 84 is suitably anchored to the motor extension 85, and by the adjustment of the screw 87 may be caused to exert frictional resistance to the revolution of the nut 82.

The drilling mechanism above described may be suitably adjusted relative to the coal face, and caused to drill blast holes in the coal body at any preferred angle to the line of advance of the mining machine, in-the usual and well known manner of operating such mechanism.

To effect greater economy of time, the mechanism above described may be caused to drill the blasting holes in-the coal body simultaneously with the formation of the kerf. In such case the supporting bars 67 will be longitudinally adjusted, and the brackets 66 rotated about their pivots to position the cutting mechanism in alinement with the point in the coal face at which the hole is desired. The clamping screw 69 is then adjusted to prevent longitudinal movement of the bar 6'7, and the rod i0 is connected with the bar 67 and with the appropriate aperture '71 in the flange 72 of the supporting frame, to retain said bar in the preferred angular relation. The drilling mechanism is then turned upon the socket 73 and the trunnions 75 to cause the feed shaft 79 and the drill bit 81 to extend towards the coal face along lines parallel with the track rails 3. The adjusting screw 83 is then manipulated to clamp the feed nut 82 securely to the feed shaft 79, and the adjusting screw 87 is manipulated to release the brake band 86 and allow the feed nut 82 to freely turn with the feed shaft. When new the drilling motors 76 are actuated and the truck 1 moves bodily towards the coal face, the drill bits 81 will be forced into the coal to form blast holes therein.

It is to be understood that I do not limit myself to the precise construction here described and illustrated, as these devices may be subject to wide variation without departure from the spirit of my invention.

What I claim is:

1. In a machine of the class described, the combination of a frame, a kerf cutter mounted on" saidframe and projecting forwardly thereof, a drill, means longitudinally adjustable of the machine and carried entirely thereby for supporting said drill in connection with said frame, means for locking said supporting means in adjusted position, said drill including a rotating bit, alternatively operable means to positively displace said bit longitudinally of the drill to engage a coal face in front of the machine independently-of the kerf cutter, and means to advance said frame.

bodily to simultaneously engage said cutter and bit with the coal face without longitudinal displacement of the bit relative to the drill.

2. In a machine of the class described, the combination of a frame, a kerf cutter mounted on said frame and projecting forwardly thereof, a drill, means longitudinally and laterally adjustable of the machine and carried entirely thereby for supporting said drill in connection with said frame, means for locking said supporting means in adjusted position, said drill including a rotating bit, alternatively operable means to positively displace said bit longitudinally of the drill to en-- gage a coal face in front of the machine independently of the kerf cutter, andmeans to advance said frame bodily to simultaneously'engage said cutter and bit with the coal face with- 3. In a machine of the class described, the combination of a mainframe, a kerf cutter mounted on said frame and projecting forwardly thereof,

a drill, means longitudinally and laterally adiultable of the machine and carried entirely thereby for supporting said drill in connection with said frame, said means including a pair of horizontally extending legs pivoted together and means for securing the other ends of said legs to said frame at variably spaced points thereon, said drill including a rotating bit, alternatively operable means to positively displace said bit longitudinally of the drill to engage a coal face in front of the machine independently of the kerf cutter, and means to advance said frame bodily to simultaneously engage said cutter and bit with the coal face without longitudinal displacement of the bit relative to the drill.

4. In a machine of the class described, the.

combination of a frame, a kerf cutter mounted on said frame and projecting forwardly thereof, a drill, means longitudinally and laterally adjustable of the machine and carried entirely thereby for supporting said drill in connection with said frame, said means including a horizontal arm laterally extensible relative to the machine and a brace connecting the free end of said arm with the frame, said drill including a rotating bit, alternatively operable means to positively displace said bit longitudinally of the drill to engage a coal face in front of the machine independently of the kerfcutter, and means to advance said frame bodily to simultaneously engage said outter and bit with the coal face without longitudinal displacement of the bit relative to the drill.

5. In a machine of the class described, the combination of a frame, a kerf cutter mounted on said frame and projecting forwardly thereof, a drill, means longitudinally and laterally adjustable of the machine and carried entirely therej cutter, and means to advance said frame bodily to simultaneously engage said cutter and bit with the coal face without longitudinal displacement of the bit relative to the drill.

6. In a machine of the class described, the combination of a frame, a drill, means longitudinally and laterally adjustable of the machine for supporting said drill in connection with said frame, said means including a horizontal arm laterally extensible and swingable in horizontal planes relative to the machine and a brace in connection at one end with the free end of said arm, the other end of said brace being pivotally connectible to said frame at a plurality of selective points.

"I. In a machine of the class described, the combination of a frame, a kerf cutter mounted on said frame and projecting forwardly thereof, means to advance the frame to feed the kerf cutter into a working face, means to swing the kerf cutter while it is engaged in the coal face and while the frame is stationary, a drill bit, means adjustable longitudinally of the frame and carried entirely thereby for supporting the bit, said bit being engageable with the working face to form a bore therein during and in dependence upon the advance of the frame, and means to project the bit 9. In a machine of the class described, a frame,

a horizontal shaft journalled on said frame, a kerf cutter mounted for swinging movement about said shaft as an axis, a motor, means for reversibly driving said shaft from said motor, and means for swinging said bar comprising a screw spindle journalled on the frame for rotation about a constant axis relative to the frame, a nut mounted on said spindle, a link in connection with said nut and cutter bar, and means for driving said spindle from said shaft whereby said nut may be reciprocated and the cutter bar swung through the intermediary of said link.

10. In a machine of the class described, a frame, a horizontal shaft journalled on said frame, a kerf cutter mounted for swinging movement about said shaft as an axis, a motor, means for reversibly driving said shaft from said motor, and means for swinging said bar comprising a screw spindle .journalled on the frame for rotation about a constant axis relative to the frame,. a nut mounted on said spindle, a link inconnection with'said nut and cutter bar, and means for driving said spindle from said shaft whereby said nut may be reciprocated and the cutter bar swung through the intermediary of said link, the driving means between the shaft and spindle including change speed gearing. I

11. In a machine of the class described, a frame, a driven shaft mounted on said frame, a sleeve mounted freely on said shaft, a cutter bar extending at right angles to said shaft and supported by said sleeve, a drive sprocket fixed on said shaft in the plane of said cutter bar, an endless cutter chain engaged by said sprocket and circulatable along the edges of said cutter bar, an angularly projecting arm fixed to said cutter bar, a screw spindle on the frame extending at right angles to said shaft and rotatable about a constant axis relative to the frame, a nut mounted on said spindle, a link connecting said nut and arm, and means driven by said shaft for rotating said spindle.

12. In a machine of the class described, a frame, a driven shaft mounted on said frame, a sleeve mounted freely on said shaft, a cutter bar extending at right angles to said shaft and supported by said sleeve, a drive sprocket fixed on said shaft in the plane of said cutter bar, an endless cutter chain engaged by said sprocket. and circulatable along the edges of said cutter bar, an angularly projecting arm fixed to said cutter bar, a screw spindle on the frame extending at right angles to said shaft and rotatable about a constant axis relative to the frame, a nut mounted on said spindle, a link connecting said nut and arm, and means driven by said shaft for rotating said spindle at either of a plurality of speeds.

13. In a machine of the class described, a frame, a driven shaft mounted on said frame, a sleeve mounted freely on said shaft, a cutter bar extending at right angles to said shaft and supported by said sleeve, a drive sprocket fixed on said shaft in the plane of said cutter bar, an endless cutter chain engaged by said sprocket and circulatable along the edges of said cutter bar, an angularly projecting arm fixed to said cutter bar, a screw spindle on the frame extending at right angles to said shaft and rotatable about a constant axis relative to the frame, a nut mounted on said spindle, a link connecting said nut and arm, a second shaft parallel to said spindle, driving connections between the first mentioned shaft and said sec ond shaft, and driving connections between said second shaft and said spindle.

14. In a machine of the class described, a frame, a driven shaft mounted on said frame, a sleeve mounted freely on said shaft, a cutterbar extending at right angles to said shaft and supported by said sleeve, a drive sprocket fixed on said shaft in the plane of said cutter bar, an end-" less cutter chain engaged by said sprocket and circulatable along the edges of said cutter bar, an angularly projecting arm fixed to said cutter bar, a screw spindle on the frame extending at right angles to said shaft and rotatable about a constant axis relative to the frame, a nut mounted on said spindle, a link connecting said nut and arm, a second shaft parallel to said spindle, driving connections between the first mentioned shaft and said second shaft, and driving connections between said second shaft and said spindle, said last named connections including change speed gearing.

15. In a machine of the class described, a wheel mounted frame, a cutter bar pivotally supported by said frame for swinging movements in a vertical plane, a transverse shaft rotatably supported by said frame on an axis parallel to a line parallel to the swinging axis of said cutter bar, a motor supported by said frame, a motor driven shaft extending at right angles to said transverse shaft, transmission means between said motor driven shaft and said transverse shaft including reversing mechanism whereby said transverse shaft is adapted to be driven in either direction, a further shaft rotatably supported by said frame on an axis parallel to the axis of said motor driven shaft, a driving connection between said transverse shaft and said further shaft, a

screw supported by said frame on an axis parallel to a line parallel to said further shaft and adapt d to be driven by the same, a nut reciprocable on said screw by reason of the reversibility of said transverse shaft, and a link pivotally connecting said nut and said cutter bar whereby the latter is swingable in accordance with the direction of movement of said nut.

16. In a machine of the class described a wheel mounted frame, 'a chain carrying cutter bar pivotally supported by said frame for swinging movements in a vertical plane, a transverse shaft rotatably 'supported by said'frame on an axis parallel to a line parallel to the swinging axis of said cutter bar, a chain driving sprocket on said shaft, 9. motor supported by said frame, a motor driven shaft extending at right angles to said transverse shaft, transmission means between said motor driven shaft and said transverse shaft including reversing mechanism whereby said transverse shaft is adapted to be driven in either direction, a further shaft rotatably supported by said frame on an axis parallel to the axis of said motor driven shaft, 2. driving connection between said transverse shaft and said further shaft, a screw supported by said frame on an axis parallel to a line parallel to said further shaft and adapted to be driven by the same, a nut reciprocable on said screw by reason of the reversibility of said transverse shaft, and a link pivotally connecting said nut and saidcutter bar whereby the latter is swingable in accordance with the direction of movement of said nut.

17. In a machine of the class described, a wheel mounted frame, a cutter bar pivotally supported by said frame for swinging movements in a vertical plane, a transverse shaft rotatably supported by said frame on an axisparallel to a line parallel to the swinging axis of said cutter bar, a motor supported by said frame, a motor driven shaft extending at right angles to said transverse shaft, transmission means between said motor driven shaft and said transverse shaft including reversing mechanism whereby said transverse shaft is adapted to be driven in either direction, a further shaft rotatably supported by said frame on an axis parallel to the axis of said motor driven shaft, 9. driving connection between said transverse shaft and said further shaft, a screw supported by said frame on an axis parallel to a line parallel to said further shaft, change speed drive mechanism between said further shaft and said screw, a nut reciprocable on said screw by reason of the reversibility of said transverse shaft, and a link pivotally connecting said nut and said cutter bar whereby the latter is swingable in accordance with the direction of movement of said nut.

18. In a machine of the class described, a wheel mounted frame adapted to travel on a minetrack, a pair of arms pivotally mounted on said frame and swingable horizontally to position their free ends in various-spaced relations laterally of the frame at opposite sides thereof, rotary drilling tools pivotally supported on the free ends of said arms respectively so as to be positionable in parallel relation to the longitudinal axis of the frame in various angular relations of said arms to said axis and at equal distances at the sides of said axis, means for holding said arms in adjusted position, means for rotating said drilling tools, and means for advancing the frame whereby said tools may be engaged in a face in advance of the frame and at variously spaced points on said face determined by the position of said arms to drill holes in said face parallel to the line of advance of said frame.

19. In a machine of the class described, a wheel mounted frame adapted to travel on a mine track, a pair of rotary drilling tools, means for rotating said tools and reciprocating them on their own axes; means supporting said tools on said frame for positioning at opposite sides of the longitudinal axis thereof, for adjustment toward and away from said axis with the axes of said tools parallel to the longitudinal axis of the frame, and for adjustment in the longitudinal direction of said longitudinal axis relative to the frame; and means for advancing the frame whereby said tools may be engaged in a face in advance of the frame and at variously spaced points on the face determined by the adjustment of said tools to drill holes in said face parallel to the line of advance of said frame.

NILS D. LEVI N. 

